It’s hard to think of a recent documentary that wastes more potential than Cropsey. The directing team of Barbara Brancaccio and Joshua Zeman start out promisingly, with an engrossing opening twenty minutes before settling into a familiar pattern of bland archival footage and talking heads.

The film follows an urban legend that has been handed down through generations of Boy Scout camps along the Hudson River Valley. The legend tells of a deranged killer named “Cropsey” who kills children that stray away from the familiar safe places and go into the woods. Depending on the storyteller, “Cropsey” uses either a hook attached at the wrist, a hatchet, axe, or any other number of sharp implements to hack people into little pieces. Growing up on Staten Island, Brancaccio and Zeman had heard the stories and assumed that they were just scary tales told to keep kids from playing in the abandoned mental hospital that sat decaying practically in their back yards. But when children started disappearing from the area, the idea that some form of the urban legend might be real started to take shape.

When the film sticks to the examination of how urban legends might be based in a small kernel of truth, Cropsey is a very interesting piece of work. Unfortunately, when a former orderly at the mental hospital is arrested for the kidnapping and murder of one of the missing children, the film takes a right turn into the unsatisfying territory of a Dateline NBC report. Questions about the guilt of the orderly are raised as he is convicted of kidnapping, but not murder. The police have nothing but circumstantial evidence, but the orderly is so creepy and weird, everyone wants to believe he’s guilty. Not surprisingly, it’s a mystery that will probably never be solved, so the film follows this track until it runs out of steam and slowly limps to a halt.

This is a real shame considering some of the chilling details that the filmmakers came across, but basically ignored in the chasing of a more conventional story. Footage of an old Geraldo Rivera report from the ’70s shows the horrific living conditions in the mental hospital when it was still operating. Half-clothed children and teens with various mental disabilities are crammed into rooms and left to roll around on the floor in their own filth, receiving no medical or psychiatric treatment. Likewise, footage of the abandoned tunnels under the hospital raise goosebumps as they are found to contain signs that people still live there. When it’s revealed that many of the children who were patients at the hospital were simply released when the hospital was closed down, I couldn’t believe it. But that was before the news that many of the people now living in the tunnel system are those kids having grown up, basically feral on the streets and in the woods surrounding the hospital. This is a much more fascinating and horrifying story than the routine film that Brancaccio and Zeman chose to make.

To me, the best documentaries are the ones that start out with the intention of telling one story, but end up going in an entirely different direction. This is because something much more interesting was uncovered in following the original story. There is a great power for the audience in that feeling of discovering something along with the filmmakers. Cropsey had every opportunity to be one of those documentaries. The filmmakers just failed to follow the more interesting discoveries and ended up with a run-of-the-mill crime story.

Matt Wedge is a writer and film critic currently doing time in the suburbs of Connecticut.